Center of Mass
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- Опубліковано 11 січ 2013
- Center of Mass and stability demonstrations
It is useful to note that the mass-center is a fixed property for a given rigid body (e.g. with no slosh or articulation), whereas the center-of-gravity may, in addition, depend upon its orientation in a non-uniform gravitational field. In the latter case, the center-of-gravity will always be located somewhat closer to the main attractive body as compared to the mass-center, and thus will change its position in the body of interest as its orientation is changed.
In the study of the dynamics of aircraft, vehicles and vessels, forces and moments need to be resolved relative to the mass center. That is true independent of whether gravity itself is a consideration. Referring to the mass-center as the center-of-gravity is something of a colloquialism, but it is in common usage and when gravity gradient effects are negligible, center-of-gravity and mass-center are the same and are used interchangeably.
Excellent explanation with practical approach. The best video on this topic!
Here in India we like your lectures a lot.great clarity.sir...Love from India
Muy interesante la explicación con cosas sencillas. Muchas gracias. Seguiré viendo sus videos. Saludos desde aqui Lima Perú presente...
After hearing people explain why men cant do the 'chair challenge' but women can, I had to find out the real reason and how to explain the difference.
Thank you so much, my brain feels at peace again. Lol
Que bueno Sr. David!!
Really good Mr.David!!
Gracias thanks merci....grazas
very nice ...thanks for this ...I went back to this old school logics before I prepare myself to order an outdoor Almirah with wheels underneath. And this video has certainly helped !!
Thank you. I love this. It really gets the concept across. I'm teaching Calculus 3 students how to use multiple integrals to calculate the coordinates of the center of mass of an object. The textbook is full of formulas and details, but I wanted to open with something more conceptual. This is perfect.
You're a genius!! Thank you SO much for this!
Just awesome. Thanks for the video.
This is an amazing method of explaining a physics topic !!
Very nicely explained! Thanks!
Thanks mate! Your video is amazing!
Really you have done a great job , I am really proud of you , in 2 years I am gonna be physics teacher and I hope to be as good as you and have that same ambition
Oshy Chan so are you a teacher now?
@@zuhaibsharifi4021 🤣🤣
now you've been teaching since 4 years !!
It's been 5 years now!!!
It's been 6 years now
I APPRECIATE YOUR EFFORTS SIR! A PRODUCTIVE 10MINS FOR MY EXAMS,THANKS A LOT!
REMEBERING THIS VIDEO WAS A DECADE BACK,WOAHHH!👌
I learnt a lot about centre of mass. I would definitely apply these demonstrations to my students. Thank a lot Sir
❤❤ amazing teaching technic❤
Thank you a lot. I am in 9th grade and my concept got clear because of you. Thank You.😁😁
This is an amazing video thank you so much!
Your the man David.
Excellent explanation
Your explanation is above of excellent
Nicely explained Professor!
The best explanation ever !!
Really good video! Learning this stuff now in college!
Excellent explanation
very helpful video thank u...
You are an amazing teacher ,and must be a good human too :)
Yeh probably he is
Thanks for the demo
Beautiful 😍.. I love you Physics
nicely explained ,,,,,... :)
Nice one....
This is gold Sir
Excellent
To account for that, you could put a nail in the "thickness"or z axis side of the block and use a weight on the end of a string to find the line where the center of gravity must lie. Then, if you know the center of mass for the block if it were of uniform thickness (the center of mass for the x and y axis), you find their intersection.
great vid
Thanks. It helped me understand
VERY WELL EXPLAINED SIR....
Awesome thank you so much
super experience of support is given for me
you nailed it.
Very well explained Sir
Nicely explained
you are a very goooooooooood teacher thanks
cool video..............
Thanks for sharing! Those are some great center of mass demonstrations!
Amazing
It’s so fascinating
excellent....
Thanks. Good video.
That really helped :)
excellent
it was just amazing to hear you !!! ,thanks a lot !!!
7:12 rockets only use rcs thrusters for docking, for stability they use gimbal in the main engine.
Thank you.
I stand corrected on how a rocket keeps the center of mass above the propulsion force. Here's a video demonstration of how the gimbal can alter the direction of the rocket's thrust. ua-cam.com/video/7196ru3wpjA/v-deo.html
thanks bro
What is the geometrical correlation between the shape and the downward force if gravity?
Dear Professor,
Terrific ! I've understood "center of mass" after watching your video ! Thanks a lot. But I have one question: I've read about the mass of center or "barycenter" of the earth-moon system; it is somewhere inside the earth ! In your video, the mass of center in inside only one object ( a piece of wood, a plastic bird or a rocket ......) whereas the earth and the moon are two totally different objects thousands miles away with no connection. How can they be considered as an object to have a common center of mass ?
Silly Jack.
Centre of mass among two particles can be calculated...
Can you explain mathematically why we can always find a line through a lamina (eg a horizontal line y=a in some coordinate system on the lamina) such that the moments on either side of this line sum to zero. It's intuitively obvious physically (hanging plumb lines etc) as you describe here but I just can't prove this mathematically. The mathematics involves the integral of all the moments of every point mass of the lamina on either side of such a line, putting this integral equal to zero and solving for the coordinate of the centre of mass. But why can we always assume we can put such an integral equal to zero in the first place.
hello proffesor what do call that string?
Good
that's good coz you re tching us more things than what we know
A lifesaver
First of all, you are really very good sir and your videos are the most beneficial for practical explanation to elementary level students!
Now my question is, does center of mass/gravity location depends upon the density of the material, and so the stability of that object? For example, I have a stick of wood and a same size stick of Iron, so, will there be any difference between the center of mass? Also, will it effect the effectiveness of balancing them on hand like you did with the broom stick?
Hello ***** , irrespective of the density of the material if should have the same center of gravity and mass provided it has the same material throughout. That is to say, the equilibrium point is dependent on the geometrical shape (that is only when it is the same material)
So is center of mass us the same as center of gravity for at least objects at earth?
Is center of gravity just force down but isnt same as center of mass
good
Wow!!!!
Great. But, I would like to ask what if the thickness of wooden blocks shown in the first two experiments (regular and irregular shapes) is not uniform? Where is the centre of mass by looking at 3-D model?
This is the closest to magic I have witnessed
At 9:12, both the cups do not have the same volume of water right? What does the ping pong ball do, that makes the centre of mass higher in the cup on the left?
Since there is no water inside the ping-pong ball, the center of mass of the water is higher. The amount of water is less, but the "point at which all the water's mass seems to be" is now higher than in the cup without the ping-pong ball.
but why? Another concept I don’t quite understand is how an object’s center of mass can be outside the very object itself. ( the Fosbury flop )
Physics is awesome
so, in the last experiment, if you'd placed a golf ball (a heavy one) in the cup instead of a ping pong ball, the cup with only water would've tipped first, right?
Yes, that's right. The c.o.m. would be lower and the cup would be more stable with a golf ball in the bottom. An extreme example of this would be the keel of a sailboat - very large mass at the bottom of the boat making it difficult to tip it over.
@@davidtaylorfuhsd thank you so much for the answer Sir. This video is just brilliant.
7:00 This would make an interesting practicle...
👍👍👏👏🙏
But the cups don’t have the same amount of water
I don't think they have the same amount of water because the ball takes some of the spaces in the cup. You need to measure the water first and put equal amount of water in both cups.
+TES HAI It is the level of the water that is the same and not the actual volume of water. The fact that the ball takes up space with air is what causes the center of gravity to be higher in the cup with the ball.
is there a difference between center of gravity and center of mass?
It is useful to note that the mass-center is a fixed property for a given rigid body (e.g. with no slosh or articulation), whereas the center-of-gravity may, in addition, depend upon its orientation in a non-uniform gravitational field. In the latter case, the center-of-gravity will always be located somewhat closer to the main attractive body as compared to the mass-center, and thus will change its position in the body of interest as its orientation is changed.
In the study of the dynamics of aircraft, vehicles and vessels, forces and moments need to be resolved relative to the mass center. That is true independent of whether gravity itself is a consideration. Referring to the mass-center as the center-of-gravity is something of a colloquialism, but it is in common usage and when gravity gradient effects are negligible, center-of-gravity and mass-center are the same and are used interchangeably.
@@davidtaylorfuhsd thanks for the explanation
Bit confusing because you keep changing between the terms center of mass and center of gravity. Otherwise nice demonstration.
Am I the newest person to watch this?
That's not teaching that's art..
#vov prof.
4:04
😘
the center of mass of an object is in the center
he looks like he is doing this on gunpoint
Ok
Plum bob
u talk about cog and then ur title is com.....hmmmm...it is not the same
For these objects it is.
Although the title says "center of mass", he keeps talking about "center of gravity". Even tough, they could be in the same spot, they are not the same. This video did not help me at all.
+Roberto Ganoza www.quora.com/Whats-the-difference-between-the-centre-of-gravity-and-the-centre-of-mass
aren't you confusing Center of Mass with Center of Gravity
In our experience here on Earth with the objects most of us deal with everyday, the center of mass and the center of gravity are in the same location. Very large objects where the pull of gravity can be different on the same amounts of mass due to the large distances involved, are not encountered in our everyday life.
@@davidtaylorfuhsd ok
Mr Chen Sent Me Here?Anyone Else?
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